Thread cutting tool



Sept. 23, 1941. Q Z|MMERMANN 2,257,029

THREAD CUTTING TOCL Filed July 3, 1941 2 Sheets-Sheet 1' 3 ai JWW 7harlea fimmrmnnn 3 THREAD CUTTING TOOL Filed July 3, 1941 2 Sheets-Sheet2 7 56 if JJ J6 17 J5 M Z, M W 4! #9 59 51 vide means whereby PatentedSept. 23, 1941 UNITED STATES PATENT orrics 2,257,029 THREAD CUTTING TOOLCharles Zimmermann, Cincinnati, Ohio Application July 3, 1941, SerialNo. 401,032

9 Claims.

This invention relates to a tool of simple construction adapted to beused for cutting threads in rods, pipes and the like, and moreparticularly to a tool provided with a plurality of cutting bits forengaging the member longitudinally spaced points relatively thereto.

More particularly, it is an object of the invention to provide a threadcutter of simple construction adapted to be readily attached to aconventional lathe and which is adapted to be supported thereby forengaging a member to be threaded which is rotatably mounted in thelathe.

A further aim of the invention is to provide a thread cutting toolhaving means whereby the cutting depth of the various varied relativelyto one another thus providing means whereby each of the cutting bitswill partially form the thread to thus reduce the amount of pressure oneach of the bits to permit the cutting operation to be performed at amuch greater speed than with conventional thread cutters having but asingle cutting bit.

Still another object of the invention is to provide means for adjustablypositioning the cutting bits relatively to one another so that thespaces between the cutting bits can be varied for forming a thread ofany desired pitch.

Still a further aim of the invention is to prothe individual cuttingbits can be readily released and moved to retracted positions so thatwhile certain of the cutting bits are in projected, operative positionsfunctioning for cutting the thread, other of the cutting bits can be inretracted positions and out of engagement with the member beingthreaded.

Other objects and advantages of the invention will hereinafter becomemore fully apparent from the following description. of the drawings,which illustrate a preferred embodiment of the thread cutting tool, andwherein-- Figure 1 is a top plan view of the tool,

Figure 2 is an end view in elevation of the same, showing the tooldetachably clamped to a portion of a lathe,

Figure 3 is a cross sectional View taken substantially along the planeof the line 3-3 of Figure 1,

Figure 4 is a longitudinal vertical sectional view taken substantiallyalong the plane of the line 4-4 of Figure 2,

Figure 5 is an enlarged horizontal sectional view of a portion of thetool, taken substantially along a plane indicated by the line 5-5 ofFigure 3,

to be threaded and at cutting bits can be Figure 6 is a verticalsectional view taken substantially along the plane of the line 6-6 ofFigure 5,

Figure '7 is a vertical sectional view taken substantially along theplane of the line I-'I of Figure 1,

Figure 8 is a horizontal sectional view of a portion of the tool takensubstantially along a plane indicated by the line 8-8 of Figure 3, and

Figure 9 is a plan View, on a reduced scale, of a guide for setting theindividual cutting bits, relatively to one another.

Referring more particularly to the drawings, wherein like referencecharacters designate like or corresponding parts throughout thedifferent views, I0 designates generally a portion of a lathe carriagewhich is provided with an upwardly opening inverted T-shaped slot I I,as best seen in Figures 2 and 3. I2 designates a portion of theheadstock spindle of the lathe, not shown, to which is connected in anysuitable manner, a piece of work I3, which is illustrated as a rod andwhich is intended to be threaded by the thread cutting tool, designatedgenerally Id. The parts I0 and I2 form parts of a conventional lathe andform no part of the present invention but are shown and described merelyto better illustrate the application and use of the thread cutter I4which is not a part of the lathe but which is adapted to be detachablyconnected thereto and to operate in conjunction therewith. The threadcutting tool I4 includes an elongated base I5 which is mounted on thecarriage l0 longitudinally of its slot I I. The base I5 is provided withremovable upstanding end walls It having upwardly and rearwardlyenlarged rear portions H. A plate I8 is detachably supported at its endson the upper edges of the forward portions of the end walls I6. BoltsI!) extend through registering openings 20 in the end walls I8 and theends of the plate I8, and said bolts 59 extend into threaded openings 2|in the ends of the base IE to provide means whereby the lower, threadedends of the bolts I9 are threadedly connected to the base I5 fordetachably securing the end walls I6 to the base and the plate I8 to theupper edges of the end walls IS. A bolt 22 extends through the parts I5,I6 and I6, at each end of the tool I4. The bolts 22 are provided withlower threaded ends which extend into the slot II and which engagethreaded openings 23 in the ends'of a bar 24 which is disposed in theenlarged, bottom portion of the slot II for clamping the thread cuttingtool I4 to the carriage I0.

As seen in Figure 3, the plate I8 combines with the top of the base l5to form an elongated horiprovided at its rear end with an T-shaped slot45. A feedscrew Which, is secured at zontally disposed slot 25 whichopens outwardly of the front side 26 of the tool l4 and which also opensoutwardly of and terminates near the rear side 21 of the base l5. Theplate I8 is provided with a longitudinally extending, elongated opening28 near the front side 26 and which opens into the slot 25. A pluralityof guides, designated generally 29 are slidably mounted in the opening28, and inthe embodiment of the invention as disclosed, three guides 29are provided. The guides 29, as best seen in Figures 3 and '7, eachincludes an enlarged lower portion 30 which is disposed in the slot 25and which is provided with a downwardly opening slot 3| which extendstherethrough, transversely of the tool M. The

guide 29, above its enlarged portion-3B, is provided with a restrictedportion 3 2 which is dis posed in slidable engagement with the opening28 and which combines with the portion 35 to form a surrounding shoulder33 which engages the underside of the plate l8. its portion 32, isprovided with a restricted up wardly extending externally threaded post34 having a threaded longitudinally extending bore 35 for receiving ascrew 36, the head of which is disposed above the upper end of the post34. A washer 31 is 'mounted on the post 34 and rests against theupper-side of the plate I8, and a nut 38 engages the threaded portion ofthe post 34, above the washer 31. The nut'38 may be of any conventionaltype and is illustrated as being of a type adapted to'be turned by meansof a spanner wrench, not shown. 7

An elongated cutting bit 39 extends through the slot 3| of theeachguide29. The number of cutting bits 39 corresponds to the number ofguides 29, and said cutting bits 39 are disposed in the slot 25 andtransversely of the tool i4, and are provided with sharpened cuttingends 48 which project outwardly from the front side 28 of the tool14.

Referring toF'igures3, and 6, the cutting bits 39 oppositely disposedoutwardly opening recesses 4|. ,Each' of thebits 39 isconnected to ablock 42. Each. block 42 is provided with a forwardly opening recess43-forv receiving the recessed rear end of a bit 39. The blocks? isprovided with set screws 44, disposed on opposite sides of the recess 43and whichextend inwardly thereof for engaging the recesses 4! fordetachablyconnecting the block 42 to thebit 39.. The block 32 isupwardlylopening 45'is connected to each of the blocks 42.. Each feedscrew 46 is provided with an outer headed end 41 and an in ner end whichis provided with a collar 48, a restricted stern portion 49 whichprojects outwardly from the collar 48, and a head 50 on the outer end ofthe stem 49. Stem? and head 56 turnably engage theT-shaped slot 45 forswivelly connecting the feed screw 46 to the block 42. Blocks 42: reston top of the base I 5 and are disposed in or partly'in the slot 25, asseen in Figure Each of the feed screws 46 is provided with a collar ornut 5| which is turnably mounted on the threaded shank portion thereof,as best seen in Figure 4. The collars or nuts 51 are provided withdiametrically opposed outwardly projecting The portions ll of the endwalls I 6 are provided, adjacent their rear ends, with alined openings53 for receiving the ends of a rod 54 which extends therebetween and itsends to the portions H by setscrews 55. Three levers 56 are pivotallyGuide 29, above are provided, near their opposite ends, with are adaptedto loosely engage in the mounted near their lower ends on the roo 54.The levers 56 are provided with openings 5! through which the rod 54loosely extends so that the levers 56 are not only pivotally butslidably mounted on the rod 54. Levers 5B are provided with handleportions 58 at their upper ends, and at their lower ends, the levers 53are bifurcated as seen at 59. As seen in Figures 2 and 3, the furcations69 of each of the bifurcated portions 59 are each provided with acorresponding downwardly opening slot 6|. portions 59 is adapted toengage loosely over a nut or collar 5! and the pair of pins 52 thereofslots M of the furcations 60 thereof for pivotaily and slidablyconnecting each lever 5'0 to a feed screw 46.

' The portions l1, adjacent their forward ends, 7 areprovided withalined openings 62 for receivingthe round ends of a rod or shaft 53. Theportion of the shaft 53 which is disposed between the endwall portionsI1 is square in cross section, as seen inFigureS, and the rounded endsof the shaft 63 are prevented from rotating in the openings 62 by meansof set screws 64, which provide means for securing the shaft'63 so thatits sides are at any desired angles relatively to the horizontal andperpendicular and, as seen in Figure 3, one side of the shaft 63 facesupwardly and slightly rearwardly. A latch arm 65 is pivctally mounted ona screw 66, intermediate of Latch arms are its ends, on each lever 56.pivotally connected to the levers 55 between the rod 54 and their upper,handle ends 58. Each latch member 65 is provided with a handle portionfil at its upper end. The lower ends of the latch members 65 are eachprovided with a flat 63 to prevent the levers 56 from being swungforwardly of the threadcutting tool l4, at their upper ends.

6An anchor member ii! is mounted in each lever 9 1'2 tendto of thelevers 55 forwardly andthejlatch members are provided to retain thelevers 53 n the full ,line positions of Figures 2 and 3 against theaction of the springs 12. 7 l, The lathe carriage I9 is adapted to bemoved parallel to the longitudinal moving the cutting tool l4 in asimilar direction. The work i3 is adapted to be revolved by theheadstock stem l2 and the rotation thereof is synchronized with themovement of the carriage H), in a conventional Each of the bifurcatedurge the upper ends 7 latch members 55, carried thereby, in theposition, as indicated in full lines in Figure 2 so that the cuttingbits 39 will be in projected positions. The cutting bits 39 can then beadjustedforwardly or rearwardly by turning their follower screws 49 toposition them to cut to the desired depth, and the bits 39 arepreferably positioned so that the leading bit 39 will partially form thethread, the intermediate bit 39 will further complete the cut, and thebit 39 at the opposite end of the tool I will complete the finished outto form the thread. By loosening the nuts 38 the guides 29 can be slidlongitudinally of the tool I4 and the feed screws 46 connected to thebits 39 of the guides 29 and the levers 56, connected to the feed screws49, will, together with the feed screws, be moved in conjunction withthe guides 29 and the bits 39 to thus provide means for adjustablypositioning the bits relatively to one another so that they cancooperate to cut threads of any desired leading cutting bit 39 hascompleted its cutting operation on the rod l3 and has been released by adownward pressure on the latch handle 61 which released the latch of thelever 53 associated with the bit, so that its spring 12 could retractthe leading bit to prevent it from striking the spindle I2. As a result,this leading bit 39 is disposed in an inoperative position while theother two cutting bits are still functioning, and it will be readilyapparent that this could readily be accomplished without interruption ofthe operation of the tool l4. In Figure 9 a setting gage, designatedgenerally A, is shown which can be employed for correctly spacing thebits 39 for cutting a thread of a certain pitch by inserting the cuttingends 40 into the notches a thereof, which are shaped to fit the cuttingends 40. The gage A can thus be employed not justing the cutting depthsof the different bits by varying the positions of the ends 49 relativelyto the notches a. It will be obvious that a plurality of guides orsetting members A could be provided having differently spaced notches a.for setting the bits 39 for cutting threads of different pitches.

It will be apparent that to release the tool M to enable it to bereturned to a position for making another cut, it is only necessary topress downwardly on the latch handles 61 to release the latches 65 sothat the springs 12 can act on the levers 56 for retracting the cuttingbits 39, inwardly of the slot 25. Consequently, if another piece of workl3, of the same diameter, is to be chased with a thread of the samedepth and pitch, it will only be necessary to return the levers 59 tothe full line position of Figure 2 to again project the bits 39 to theircorrect cutting positions, after the carriage l9 and tool i l have beenreturned to a position to begin another thread cutting operation.

The thread cutting tool can be made for any size engine lathe and thetool can be provided with either three or four cutting bits.

Various modifications and changes are contemplated and may obviously beresorted to, provided they fall within the spirit and scope of theinvention as hereinafter defined by the appended claims, as only apreferred embodiment of the invention has been disclosed.

I claim as my invention:

1. A thread cutting tool comprising a base adapted to be detachablyclamped to a portion of a lathe, said base being provided with uprightpitch. As seen in Figure 1, the

only for spacing thebits 39 relatively to one another but also foradprovided with guides slidably mounted in said slot, a plurality of endwalls, a plate'detachably fastened to said end walls and disposedaboVeJand spaced from the forward portion of said base, said plate beinga longitudinal slot, a plurality of cutting bits-slidably engaging saidguides: and disposed to move transversely ofv the base, feed screwsswivelly connected to the rear ends of; said bits and projectingrearwardly from the thread cutting tool, a collar threadedly engagingeach of said feed screws, each of said collars being provided withdiametrically opposed outwardly projecting studs, a plurality of leversslidably and pivotally mounted on the thread cutting tool, said levershaving yoke shaped lower ends for engaging over said collars, said yokeshaped ends being slotted to engage said studs, spring means for urgingthe upper ends of said levers forwardly of the tool for retracting thefeed screws and cutting bits, and latch means carried by said levers forholding the cutting bits and feed screws in projected positions.

2. A thread cutting tool as in claim 1, said guides being movablerelatively to the plate for moving the cutting bits, feed screws andlevers longitudinally of the base for adjustably spacing the cuttingbits relatively to one another.

3. A thread cutting tool as in claim 1, said guides being movablerelatively to the plate for moving the cutting bits, feed screws andlevers longitudinally of the base for adjustably spacing the cuttingbits relatively to one another, and

said guides being provided with clamping means for engaging the platefor retaining the cutting bits in adjusted positions relatively to oneanother.

4. A thread cutting tool as in claim 1, comprising a rod detachablymounted in the rear ends of said end walls and on which said levers arepivotally and slidably mounted, a second rod detachably mounted at itsends in said end walls and forwardly of said first mentioned rod, saidsecond rod being square in cross section, and said latch means includingpivotally mounted lever arms carried by said levers and having lower endportions for detachably engaging said second rod for preventing theupper ends of said levers from being swung forwardly by the action ofsaid spring means to retain the cutting bits in projected positions.

5. A thread cutting tool comprising a plurality of cutting bits, thelongitudinal axis of said tool being disposed parallel to thelongitudinal axis of the member to be threaded thereby, said cuttingbits being spaced from one another longitudinally of the tool and beingdisposed transversely thereof, guide means for slidably mounting saidbits, said guide means being movable longitudinally of the tool foradjustably spacing the bits from one another, pivotally mounted leversconnected to said bits for advancing and retracting the bits, and latchmeans associated with said levers for holding the bits in projectedpositions.

6. A thread cutting tool as in claim 5, comprising spring means fornormally urging the bits to retracted positions.

'7. A thread cutting tool as in claim 5, com prising means foradjustably connecting said levers to the bits for varying the cuttingdepth of the bits, when in their projected positions.

8. A thread cutting tool comprising a tool frame provided with aplurality of cutting bits, said cutting bits being spaced from oneanother in a direction parallel to the longitudinal axis of a member tobe threaded thereby, means for adpar-allelic one.anothen'rleversconnected-tosaid V 9. 1A thread cutting tool as in claim8; .com;

prising"meansforadjustfibly connecting said out- .ting-bits and leve rsfor adjusting ,the cutting depth. of the bits, when in projectedpositions,

cuttingmits for projecting-rand retracting-"the 5 independently'of oneanother.

cutting bits, vand; latch. :means 1 c'arrie'd by said levers vfnrholding-.1 the 5- cutting bits: in projected positions't.

CHARLES ZIMME'RMANN.

